Optical position measuring device

ABSTRACT

An optical position measuring arrangement that includes an incremental measuring graduation and a scanning unit, which can be moved in relation to the incremental measuring graduation along a measuring direction and by which position-dependent incremental signals are generated from scanning the measuring graduation. The scanning unit includes a transparent support substrate and two incremental signal scanning arrangements arranged in the measuring direction. Each of the incremental scanning arrangements includes a light source and several incremental signal detector elements, wherein the incremental signal scanning arrangements are arranged on a side of the support substrate facing away from the incremental measuring graduation. The scanning unit includes several fields with scanning gratings, each field is spatially assigned to corresponding incremental signal detector elements and is arranged between the incremental signal scanning arrangements and the support substrate, wherein the scanning gratings are arranged so that partial incremental signals with predetermined phase relations are generated from the incremental signal detector elements.

[0001] The present invention relates to an optical position measuringdevice.

[0002] A miniaturized scanning unit for an optical position measuringdevice suitable for incident light-scanning of an incremental measuringgraduation is known from the publication New Dimensions in Position andAngular Measuring Technology by R. Burgschat in F & M 104, 1996, 10, pp.752 to 756. Inter alia, the scanning device comprises an incrementalsignal scanning arrangement placed on a support substrate. Theincremental signal scanning arrangement essentially consists of aphotodiode array with a multitude of incremental signal detector areasand a centrally arranged light source. Details regarding the structureof the incremental signal scanning arrangement can also be found in DE195 27 287 A1.

[0003] A second photodiode array for generating reference pulses isarranged next to the first photodiode array for generating incrementalsignals and spaced apart from the first array in the measuringdirection. An alternative variation for generating a reference pulsesignal in such a scanning unit is moreover known from DE 199 21 309 A1.

[0004] Besides position measuring devices with only a single incrementalsignal scanning arrangement on the side of the scanning unit, alongitudinal measuring system is known from the company publication“Encoder-Kit L” of NUMERIK Jena GmbH with the designation “KitL-D-03/99”, published in March of 1999, wherein two such incrementalsignal scanning arrangements are provided, clearly spaced apart fromeach other, on a common support substrate. A continuous scanning gratingfor the two incremental signal scanning arrangements is arranged on theunderside of the support substrate which faces the scanned measuringgraduation. The generation of phase-shifted partial incremental signalsfrom the multitude of the incremental signal detector areas takes placeby means of an appropriate relative arrangement of the incrementalsignal detector areas with respect to each other.

[0005] In systems with only a single incremental signal scanningarrangement in the scanning unit, the resultant sensitivity regardingdirt on the measuring graduation has shown itself to be particularlydisadvantageous. The reason for this is a relatively small scanningfield on the scale. Faulty measurements are the result, if during themeasuring operation the scanning field is occupied by dirt particles.

[0006] In connection with the systems with two spaced apart incrementalsignal scanning arrangements also mentioned above, it is considered tobe disadvantageous that only a limited operating temperature range isavailable because of the different thermal coefficients of expansion ofthe scale and the scanning unit. This is based on the fact that becauseof the large distance between the incremental signal scanningarrangements it is no longer assured in case of temperaturerelatedposition changes that the predetermined phase positions on the variousdetector elements remain the same. Furthermore, a definite effect on thesignal amplitudes, as well as the signal offset, still results in caseof dirt on the measuring graduation.

[0007] It is therefore the object of the present invention to disclosean optical position measuring device which can be miniaturized as muchas possible, and assures a dependable generation of position-dependentscanning signals as well.

[0008] This object is attained by means of an optical position measuringdevice having the characteristics of claim 1.

[0009] Advantageous embodiments of the optical position measuring deviceensue from the characteristics disclosed in the claims depending fromclaim 1.

[0010] In accordance with the invention, at least two incremental signalscanning arrangements with two light sources are now arrangedimmediately next to each other in the measuring direction on atransparent support substrate. The generation of phase-shifted partialincremental signals from the incremental signal detector elements takesplace by means of the spatially defined assignment of scanning gratingsto the individual detector elements. In this case different fields withscanning gratings are arranged between the side of the support substratefacing away from the measuring graduation and the incremental signaldetector elements.

[0011] It can be stated as a considerable advantage of the positionmeasuring device in accordance with the invention that, besides theextremely compact construction of the system, because of theillumination of the scanned measuring graduation by means of at leasttwo light sources and the provision of an increased number ofincremental signal detector elements, the incremental signals are nowobtained from many signal portions from different scanning locations onthe measuring graduation. Isolated dirt particles on the measuringgraduation therefore have only little effect on the quality of theresulting measuring signals, in particular their amplitude. Because ofthe multiple illumination, a substantially larger field of the measuringgraduation is scanned in the course of the generation of the scanningsignals, without it being necessary to have to clearly increase the sizeof the individual incremental signal scanning arrangements, or toprovide clearly more incremental signal detector elements. In the end,the illumination of the measuring graduation by means of several lightsources is the prerequisite for the extremely compact construction ofthe scanning unit.

[0012] It can be stated as a further advantage that, because of theassignment of a suitable scanning grating to each individual incrementalsignal detector element, it is now possible to assure that therespective partial incremental signal has the correct phase position.Because of distortion effects in the scanned strip pattern, this is notassured in the case wherein a common scanning grating is used for allincremental signal detector elements.

[0013] In an advantageous embodiment of the position measuring device,several respective reference pulse detector elements are additionallyarranged laterally adjoining the at least two incremental signalscanning arrangements. The generation of reference pulse signals atdefined positions along the measuring track is possible with the aid ofthe reference pulse detector elements. Moreover, still another lightsource is arranged on each side in the area of the reference pulsedetector elements, so that there are separate light sources for scanningthe incremental measuring graduation and the reference markings. Bymeans of the employment of separate light sources for generating theincremental signals and the reference pulse signals it is possible toarrange the respective scanning tracks on the scale even further apartfrom each other without it being necessary to have to clearly increasethe size of the individual incremental signal scanning arrangements, orto provide clearly more incremental signal detector elements. In thisway a greater lateral offset as a whole of the scanning unit withrespect to the scale can also be tolerated without it being necessary toconstruct too large an incremental signal scanning arrangement.

[0014] If transmission gratings are respectively arranged in front ofthe additional light sources in the area of the reference pulse detectorelements, as well as in front of the light sources in the incrementalsignal scanning arrangements, which correspond to transmission gratingsin front of the light sources of the incremental signal scanningarrangements, substantial portions of the radiation from these lightsources can also be used for generating incremental signals. Thescanning surface on the measuring graduation is again increased by thisand also contributes to a reduction of the sensitivity to dirt.

[0015] Because of the provision of several respective reference pulsedetector elements on both sides of the incremental signal scanningarrangements, an increased flexibility furthermore results with respectto the generation of reference pulse signals. For example, all referencepulse detector elements on one side can be interconnected and thus beused for scanning a coded reference marking; alternatively to this, theinner reference pulse detector elements can be used as differencephoto-receivers for scanning simple dash-shaped reference markers, whilethe remaining reference pulse detector elements are employed ascompensation detector elements in a known manner.

[0016] It is of course possible to lay out the position measuring devicein accordance with the invention for linear, as well as rotary,applications. It is also not a problem to lay out the position measuringdevice in accordance with the invention for different measuringgraduation periods.

[0017] Further advantages, as well as details of the present inventionensue from the following description of an exemplary embodiment by meansof the attached drawings.

[0018] Shown here are in:

[0019]FIG. 1, a schematic lateral plan view of an exemplary embodimentof the position measuring device in accordance with the invention,

[0020]FIG. 2, a view from above on the scanned measuring graduation inFIG. 1,

[0021]FIG. 3, a view from above on the detector plane of the scanningunit in FIG. 1,

[0022]FIG. 4, a view from above on the support substrate of the scanningunit in FIG. 1, together with the detector elements and light sources ofthe optical scanning chip.

[0023] A schematic representation 1 of an exemplary embodiment of theoptical position measuring device in accordance with the invention isrepresented in FIG. 1. In addition to a scanning unit 20, it consists ofa scale 10 with the scanned incremental measuring graduation 12. Thescale 10 used is shown in a view from above in FIG. 2.

[0024] The scanning unit 20 and the scale 10 with the measuringgraduation 12 are arranged so they can be displaced with respect to eachother in the measuring direction x shown, thus, the measuring directionx is oriented parallel with respect to the drawing plane in FIG. 1.

[0025] The represented exemplary embodiment of the optical positionmeasuring device is used for detecting linear relative movements betweenthe scanning unit 20 and the scale 10, or measuring graduation 12. Anappropriately embodied position measuring device can be employed in anumerically-controlled machine tool, for example. The position-dependentscanning signals are transmitted for further processing to an evaluationunit, not represented, for example a numerical machine tool controldevice.

[0026] Alternatively to the linear variation shown, the positionmeasuring device in accordance with the invention can of course also bemodified for detecting rotary relative movements, etc.

[0027] In the present exemplary embodiment, the scale 10 used consistsof a support body 11, on the center of which a track with theincremental measuring graduation 12 is arranged in the measuringdirection x. Periodically arranged reflecting partial areas 12.1 andnon-reflecting partial areas 12.2 extend in the measuring direction x inthe incremental measuring graduation 12, whose longitudinal axes areeach oriented in the indicated y-direction, i.e. perpendicularly withrespect to the measuring direction x. In a possible embodiment, thegraduation period TP_(M) of the incremental measuring graduation 12 isfor example selected to be TP_(M)=20 μm. A metal tape, for example, canbe used as the support body 11, on which the partial areas 12.1, 12.2with the appropriate optical properties are embodied in the area of theincremental measuring graduation 12.

[0028] Here the type of material the scale 10 is made of is notessential for the invention, i.e. in principle the scale 10, or theincremental measuring graduation 12, can be produced alternatively tothe indicated embodiment.

[0029] Two reference markings 13.1, 13.2 at a reference position XREF intwo reference marking tracks 14.1, 14.2 are furthermore arrangedlaterally adjoining the incremental measuring graduation 12 in theexample shown. An unequivocal absolute position along the measuringtrack is defined with the aid of the reference markings 13.1, 13.2,through which the absolute relationship of the high-resolutionincremental measurement can be provided in a known manner.

[0030] It is of course also possible to arrange such reference markings13.1, 13.2 in pairs at appropriate reference positions XREF of the scale10 also at further locations along the reference marking tracks 14.1,14.2. It is also possible to provide so-called distance-coded referencemarkings, etc.

[0031] In the exemplary embodiment shown, the two reference markings13.1, 13.2, which are arranged laterally adjoining with respect to theincremental graduation track 12, have a length 1_(x)=500 μm in themeasuring direction x, the length 1_(y) of the reference markings 13.1,13.2 in the direction of the bars of the incremental graduation track 12is selected to be 1_(y)=1 mm, for example.

[0032] In this example, the reference markings 13.1, 13.2 are embodiedas non-reflecting areas on the otherwise reflecting support body 11.

[0033] Alternatively to this it is also possible to reverse thearrangement of reflecting and non-reflecting areas, so that in this caseonly the reference markings 13.1, 13.2 act reflectingly, while the restof the reference marking tracks 14.1, 14.2 is laid out to benon-reflecting. Such a variant is advantageous because the sensitivityto dirt in the course of generating reference pulse signals can be againreduced by this, since possible dirt particles on the scale do notscatter the impinging light as a rule and do not reflect in adirectional manner.

[0034] The arrangement of two reference markings 13.1, 13.2 laterallyadjoining with respect to the measuring graduation 12 offers advantagesover the arrangement of a reference marking merely on one side. Thus, bymeans of this it is practically impossible for a local dirt deposit, forexample, which also acts optically by reducing the reflection and islocated next to the incremental graduation track 12, to be interpretedas a reference marking. Reference is also made in this connection toalready mentioned DE 199 21 309 A1.

[0035] In the schematic representation in FIG. 1, a number of importantcomponents can be seen on the part of the scanning unit 20 of theposition measuring device in accordance with the invention. Inconnection with the description of the scanning unit 20, reference isalso made here to FIGS. 3 and 4, which represent a plan view of thedetector plane, as well as a view from above on the support substrate 21of the scanning unit 20, together with further elements of the scanningunit 20.

[0036] The functionally relevant elements for generating theshift-dependent scanning signals are arranged on a transparent supportsubstrate 21 in the scanning unit 20. The support substrate 21 ispreferably composed of a suitable borosilicate glass material and, in apossible embodiment, has a thickness of approximately 1 mm; in thisexample the support substrate 21 has a rectangular cross section of thedimensions of 8 mm×14 mm.

[0037] In the present exemplary embodiment the components of thescanning unit 20 to be described in what follows are all arranged on theside of the support substrate 21 facing away from the measuringgraduation 12 to be scanned. In the further course of the descriptionthis side will also be called the top, the side facing the measuringgraduation will be called the bottom. An optical scanning chip 22 isessentially arranged on the top of the support substrate 21 and itsstructure will be described in detail in what follows, as well as asignal processing module 33, which further processes the scanningsignals generated by means of the optical scanning chip 22 before theyare passed on to a suitable evaluation unit. The signal processingmodule 33 is preferably embodied in the form of a suitable ASIC here.

[0038] In the area of the optical scanning chip 22, several sections onthe support substrate 21 are embodied with grating structures 36, whichare spatially assigned to various elements of the optical scanning chip22 arranged above them. The various grating structures 36, which cannotbe seen in detail in FIG. 1, are scanning gratings and transmittinggratings, each of which has been placed in a definite spatialarrangement in front of the opto-electronic incremental signal detectorelements and the various light sources 28.1, 28.2, 30.1 of the opticalscanning chip 22. The grating structures are, for example, knownamplitude gratings in the form of periodically arranged opaque chromiumstrips on the transparent support substrate 21.

[0039] The functions and the exact design of the grating structures 36will be addressed in detail in the course of the following description.

[0040] Furthermore, a planar printed circuit board structure 35, orsingle level wiring, has been applied to further areas on the top of thetransparent support substrate 21 and is used in a known manner for theelectrical connection of the various optical, electrical andopto-electronic components with each other on the support substrate 21.The optical scanning chip 22 and the signal processing module 33 inparticular are placed into contact with each other by means of this. Theplanar printed circuit board structure 35 is connected in anelectrically conducting manner, for example in the manner of a solderedconnection with solder bumps 39, with a flexible strip conductor 34 atthe edge of the support substrate 21. The scanning unit 20 is connectedvia the flexible strip conductor 34 with a downstream arrangedevaluation unit, for example.

[0041] Alternatively to the flexible strip conductor 34 it would also bepossible to provide a miniature plug connector, or a foil plug connectorat this location of the support substrate 21.

[0042] It would also be conceivable to arrange the signal processingmodule on a level above the optical scanning chip, similar to a knownarrangement in DE 198 55 828 A1, in order to provide a three-dimensionalstructure of the scanning unit in this way.

[0043] The optical scanning chip 22, as well as the signal processingmodule 33 are fastened on the support substrate 21 by means of knownflip-chip techniques; some of the contacting pads 37.1, 37.2, . . . ,made of SnPb solder or a lead-free solder alloy, can be seen in FIG. 1in an area between the top of the support substrate 21 and therespective components 22, 33. Moreover, the spaces between the supportsubstrate 21 and the components 22, 33 arranged on it are filled with asuitable underfilling 40, 41, so that a mechanical stabilization of theentire structure results.

[0044] The construction in accordance with the invention of the opticalscanning chip 22 of an exemplary embodiment, whose detector plane isshown in FIG. 3 in a view from above, will now be explained in greaterdetail by means in FIG. 3.

[0045] In the present example, two incremental signal scanningarrangements 23.1, 23.2 of an approximately square shape are arranged onan optical scanning chip substrate 25 directly adjacent to or borderingeach other in the measuring direction x. Each of the incremental signalscanning arrangements 23.1, 23.2 contains a centrally arranged lightsource 28.1, 28.2, for example a suitable LED, and several incrementalsignal detector elements 26.1, 26.2, 27.1, 27.2 arranged distributedaround the light source 28.1, 28.2, and are embodied, for example, inthe form of known photodiodes. In the course of scanning the measuringgraduation, several phase-shifted partial incremental signals aregenerated by means of the various incremental signal detector elements26.1, 26.2, 27.1, 27.2; in FIG. 3 the number assigned to eachincremental signal detector elements 26.1, 26.2, 27.1, 27.2 indicatesthe respective relative phase position of the partial incremental signalresulting therefrom. Accordingly, in the example represented thegeneration of four different partial incremental signals is provided,which have the relative phase positions of 0°, 90°, 180° and 270°.

[0046] Basically an attempt is made to arrange the various incrementalsignal detector elements in such a way that the sum of the optical pathsof the respective phase positions is as identical as possible. Moreover,the effects of possible tilts or twists of the scanning unit withrespect to the scale on the phase-shifted partial incremental signals isintended to be compensated as much as possible by the arrangement of theincremental signal detector elements.

[0047] Equiphased partial incremental signals of the phase-shiftedpartial incremental signals generated in this way are interconnected viathe mentioned wiring circuit 35 on the support substrate 21 and are madeavailable for further processing in a known manner.

[0048] Further processing, for example in the form of signalamplification and signal interpolation, can already take place in thesignal processing module 33 of the scanning unit 20. Besides this,alternative variations of signal processing are of course also possiblein this module 33.

[0049] In the example represented, the light sources 28.1, 28.2 in thetwo incremental signal scanning arrangements 23.1, 23.2 are arranged ina suitably shaped cavity of the optical chip support substrate 25, suchas can be seen, for example, in the lateral view in FIG. 1. This meansthat the light sources 28.1, 28.2 of the two incremental signal scanningarrangement 23.1, 23.2 are arranged co-planar with respect to the frontface of the optical scanning chip 22, and the light-emitting front facesof the light sources 28.1, 28.2 do not project past this face.

[0050] In the exemplary embodiment shown, each one of the twoincremental signal scanning arrangements 23.1, 23.2 consists of a totalZ_(GES)=36 square fields, each of which has an edge length K_(F)=L; theedges of the fields are oriented parallel, as well as at right angleswith respect to the measuring direction x. In general, within a positionmeasuring device in accordance with the invention, one incrementalsignal scanning arrangement 23.1, 23.2 has Z_(GES)=n*4 fields of theedge length L, wherein n=1, . . . , 6, 7, . . . ; in the representedcase n=6 therefore applies.

[0051] Thus, K_(l)=n*L results as the edge length K_(l) for anincremental signal scanning arrangement 23.1, 23.2.

[0052] Within the incremental signal scanning arrangements 23.1, 23.2,no detector elements, such as in all remaining fields, are provided in acentral area of Z_(LQ)=4 fields; a light source 28.1, 28.2 has beenplaced in this central area in place of detector elements. RespectivelyZ_(DET)=Z_(GES)−Z_(LQ)=32 incremental signal detector elements 26.1,26.2, . . . , 27.1, 27.2. . . are arranged in the remaining surroundingfields. Altogether, the two incremental signal scanning arrangements23.1, 23.2 of this example therefore have 64 incremental signal detectorelements 26.1, 26.2, . . . , 27.1, 27.2. . . The multitude ofincremental signal detector elements 26.1, 26.2, . . . , 27.1, 27.2. . .used contributes substantially to the insensitivity to dirt of theposition measuring device in accordance with the invention.

[0053] As can be furthermore seen in FIG. 3, several reference pulsedetector elements 31.1 to 31.4, 32.1 to 32.4 are additionally arrangedadjacent to the two incremental signal scanning arrangements 23.1, 23.2of the exemplary embodiment represented. The various reference pulsedetector elements 31.1 to 31.4, 32.1 to 32.4 are respectivelysequentially arranged on each side in the measuring direction x. In therepresented example, a total of four such reference pulse detectorelements 31.1 to 31.4, 32.1 to 32.4 are provided on each side forgenerating a reference pulse signal from the scanning of an appropriatereference marking on the scale.

[0054] Furthermore, respective separate light sources 30.1, 30.2 areassigned to each group of four reference pulse detector elements 31.1 to31.4, 32.1 to 32.4 in the optical scanning chip 22; again, an LED can beused as the light source 30.1, 30.2. The respective light source 30.1,30.2 is arranged in the center of the four reference pulse detectorelements 31.1 to 31.4, 32.1 to 32.4, to which end the two centralreference pulse detector elements 31.2, 31.3, or 32.1, 32.3 have acorresponding U-shaped cutout.

[0055] The arrangement of the two light sources 30.1, 30.2 in the areaof the reference pulse detector elements 31.1 to 31.4, 32.1 to 32.4takes place analogously to that of the light sources 28.1, 28.2 of thetwo incremental signal scanning arrangements 23.1, 23.2, i.e. the twolight sources 30.1, 30.2 are also arranged in cavities of the opticalchip support substrate 25.

[0056] As already indicated above, in the course of scanning theincremental measuring graduation, the different incremental signaldetector elements 26.1, 26.2, . . . , 27.1, 27.2 . . . provide periodicpartial incremental signals with the cited relative phase positions. Incontrast to the system of the publication mentioned at the outset, thesetting, or the generation of the various phase positions of theincremental scanning signals is now no longer provided by means of thearrangement, or placement, of the incremental signal detector elements26.1, 26.2, . . . , 27.1, 27.2 . . . relative to the scanned periodicstrip pattern in the detection plane, but by means of fields, or areas,with scanning gratings which are assigned, spatially defined, to theindividual incremental signal detector elements 26.1, 26.2, . . . ,27.1, 27.2 . . . These respective fields with scanning gratings arearranged on the transparent support substrate 21 of the scanning unit20, as can be seen in FIG. 4. FIG. 4 represents a view from above on thesupport substrate 21 of the scanning unit, wherein further components,such as parts of the optical scanning chip, of the signal processingmodule 33 and the solder bumps 39 for the flexible strip conductor, canbe seen in addition in this representation.

[0057] The arrangement of a total of 64 fields with scanning gratings36.1, 36.2, . . . , 37.1, 37.2, . . . on the support substrate 21 can beclearly seen in FIG. 4, i.e. on the support substrate 21 a scanninggrating 36.1, 36.2, . . . , 37.1, 37.2 , . . . is unequivocally assignedto each field in the optical scanning chip 22 with an incrementaldetector element. In the present example, all scanning gratings 36.1,36.2, . . . 37.1, 37.2, . . . in the different fields have the samegraduation period TP_(AG), which corresponds to twice the graduationperiod TP_(M)=20 μm of the scanned incremental measuring graduation onthe scale, i.e. TP_(AG)=40 μm.

[0058] The phase position of the detected partial incremental signal isset in the various incremental signal detector arrangements by means ofthe relative position of the various scanning gratings 36.1, 36.2, . . ., 37.1, 37.2, . . . For this purpose, the individual scanning gratings36.1, 36.2, . . . , 37.1, 37.2, . . . in the various fields have offsetdistances from each other, which are dimensioned in a known manner andmake possible the generation of partial incremental signals of phasepositions of 0°, 90°, 180° and 270°. For example, the scanning gratingsfor generating partial incremental signals with the phase positions 0°and 90° have a distance D₀₋₉₀=N*TP_(M)/4, wherein N=1, 2, 3. . . ; thedistance D₀₋₁₈₀ between the 0° partial incremental signal and the 180°partial incremental signal is D₀₋₁₈₀=N*TP_(M)/2, wherein N=1, 2, 3. . ., and the distance D₀₋₂₇₀ between the 0° partial incremental signal andthe 270° partial incremental signal is D₀₋₂₇₀=N*TP_(M)/2, wherein N=1,2, 3. . . . The distances, or offset distances in FIG. 4 are of coursenot true to scale.

[0059] As can also be seen in FIG. 4, further grating structures in theform of transmitting gratings 46, 47, 48, 49 are arranged on the supportsubstrate 21 in the area of the total of four light sources, i.e. infront of the two light sources of the incremental signal scanningarrangements, as well as in front of the two light sources assigned tothe reference pulse detector elements. In the present example, thegraduation period TP_(SG) of all four transmitting gratings 46 to 49 isselected to be identical to twice the graduation period TP_(M) of theincremental measuring graduation and therefore corresponds to thegraduation period TPAG of the scanning gratings 36.1, 36.2, . . . ,37.1, 37.2, i.e. TP_(SG)=40 μm.

[0060] Thus, in the explained exemplary embodiment of the scanning unitof the position measuring device in accordance with the invention, atotal of four light sources 28.1, 28.2, 30.1, 30.2 with identicaltransmitting gratings 46 to 49 arranged in front of them are available,which assure the generation of a sufficiently large scanning field onthe measuring graduation of the scale, and therefore contribute to thedesired insensitivity to dirt.

[0061] Besides the explained example, further modifications of theposition measuring device of the invention are of course possible withinthe scope of the present invention.

[0062] It is thus possible, for example, to arrange more than twoincremental signal scanning arrangements on the part of the scanningunit. In the same way it would be possible to modify the arrangement ofthe phase positions of the incremental signal detector elements in asuitable way within the scope of the present invention. It isfurthermore also possible to provide alternative cross-sectionalgeometries for the incremental signal detector elements, or theincremental signal scanning arrangements.

[0063] Moreover, in principle it is also possible to employ a scanningunit as described above for transmitted light scanning of an appropriatemeasuring graduation; in this case it would only be necessary todeactivate the light sources in the optical scanning chip, while thearrangement of the detector elements could remain unchanged.

[0064] It should furthermore be mentioned that, alternatively to theterminology used so far, within the scope of the present invention itwould be possible to speak of a single detector array in the scanningunit with a multitude of detector elements, wherein several lightsources are assigned to the detector array, etc.

1. An optical position measuring arrangement, consisting of anincremental measuring graduation (12) and a scanning unit (20), whichcan be moved in relation to it in at least one measuring direction (x)and by means of which position-dependent incremental signals can begenerated from scanning the measuring graduation (12), and wherein thescanning unit (20) comprises the following components: a transparentsupport substrate (21), at least two incremental signal scanningarrangements (23.1, 23.2) arranged in the measuring direction (x), eachof which contains a light source (28.1, 28.2) and several incrementalsignal detector elements (26.1, 26.2, . . . , 27.1, 27.2. . . ) arrangeddistributed around the light source (28.1, 28.2), by means of whichpartial incremental signals can be generated from the scanning of themeasuring graduation (12), wherein the at least two incremental signalscanning arrangements (23.1, 23.2) are arranged on the side of thesupport substrate (21) facing away from the measuring graduation (12),several fields with scanning gratings (36.1, 36.2, . . . , 37.1, 37.2, .. . ), each of which is spatially assigned to the incremental signaldetector elements (26.1, 26.2 , . . . , 27.1, 27.2 . . . ) and isarranged between the incremental signal scanning arrangements (23.1,23.2) and the support substrate (21), wherein the various scanninggratings (36.1, 36.2, . . . , 37.1, 37.2, . . . ) are arranged in such away that partial incremental signals with predetermined phase relationscan be generated from the various incremental signal detector elements(26.1, 26.2, . . . , 27.1, 27.2. . . ).
 2. The optical positionmeasuring device in accordance with claim 1, wherein the variousscanning gratings (36.1, 36.2, . . . , 37.1, 37.2, . . . ) are arrangedon the side of the support substrate (21) which is oriented so it facesaway from the measuring graduation (12).
 3. The optical positionmeasuring device in accordance with claim 1, wherein the incrementalsignal scanning arrangements (23.1, 23.2) each consist of n*4 fields,wherein n=1, 2, 3 . . .
 4. The optical position measuring device inaccordance with claim 1, wherein each field has an edge length L, andthe edges of the square fields are oriented parallel, as well as atright angles with respect to the measuring direction (x).
 5. The opticalposition measuring device in accordance with claim 4, wherein eachincremental signal scanning arrangement (23.1, 23.2) has a square shapeand the edge length K_(l)=n*L.
 6. The optical position measuring devicein accordance with claim 3, wherein the light source (28.1, 28.2) isarranged in the center of the incremental signal scanning arrangements(23.1, 23.2) in the area of Z_(LQ)=k*4 fields, and is surrounded byZ_(DET=n) ²−(k*4) fields with incremental signal detector elements(26.1, 26.2, . . . , 27.1, 27.2 . . . ).
 7. The optical positionmeasuring device in accordance with claim 1, wherein the incrementalsignal scanning arrangements (23.1, 23.2) are arranged directlyadjoining each other in the measuring direction (x).
 8. The opticalposition measuring device in accordance with claim 1, wherein each ofthe scanning gratings (36.1, 36.2, . . . , 37.1, 37.2, . . . ) has thesame graduation period TPAG.
 9. The optical position measuring device inaccordance with claim 8, wherein the scanning gratings (36.1, 36.2, . .. , 37.1, 37.2, . . . ) which are assigned to equiphased incrementalsignal detector elements (26.1, 26.2, . . . , 27.1, 27.2. . . ) eachhave a defined offset (D₀₋₉₀, D₀₋₁₈₀, D₀₋₂₇₀) from each other in themeasuring direction (x).
 10. The optical position measuring device inaccordance with claim 9, wherein the various scanning gratings (36.1,36.2, . . . , 37.1, 37.2, . . . ) are arranged relatively offset perincremental signal scanning arrangement (23.1, 23.2) in such a way thatrespectively a plurality of four phase-shifted partial incrementalscanning signals results.
 11. The optical position measuring device inaccordance with claim 1, wherein equiphased partial incremental signalsfrom all incremental signal scanning arrangements (23.1, 23.2) areinterconnected.
 12. The optical position measuring device in accordancewith claim 1, wherein transmitting gratings (48, 49) are arranged on thesupport substrate (21) in the area of the light sources (28.1, 28.2) ofthe incremental signal scanning arrangements (23.1, 23.2).
 13. Theoptical position measuring device in accordance with claim 12, whereinthe graduation periods (TPAG, TP_(SG)) of the scanning gratings (36.1,36.2, . . . , 37.1, 37.2, . . . ) and the transmitting gratings (48, 49)are selected to be identical.
 14. The optical position measuring devicein accordance with claim 1, wherewith respectively several referencepulse detector elements (31.1, . . . , 31.4, 32.1, . . . , 32.4) arearranged sequentially in the measuring direction (x) perpendicularlywith respect to the measuring direction (x) and adjoin both sides of theat least two incremental signal scanning arrangements (23.1, 23.2). 15.The optical position measuring device in accordance with claim 14,wherein furthermore a light source (30.1, 30.2) each is arranged in thearea of the reference pulse detector elements (31.1, . . . , 31.4, 32.1,. . . , 32.4).
 16. The optical position measuring device in accordancewith claim 14, wherewith respectively four reference pulse detectorelements (31.1, . . . , 31.4, 32.1, . . . , 32.4) are arranged on bothsides adjoining the at least two incremental signal scanningarrangements (23.1, 23.2).
 17. The optical position measuring device inaccordance with claim 19, wherein transmitting gratings (48, 49) arearranged on the support substrate (21) in the area of the light sources(30.1, 30.2) of the reference pulse detector elements (31.1, . . . ,31.4, 32.1, . . . , 32.4).
 18. he optical position measuring device inaccordance with claim 12 or 17, wherein the transmitting gratings (46 to49) each have the same graduation period (TP_(SG)).
 19. The opticalposition measuring device in accordance with claim 1, whereinfurthermore at least one signal processing module (33) is arranged onthe side of the support substrate (21) facing away from the measuringgraduation (12).
 20. The optical position measuring device in accordancewith claim 1, wherein furthermore a planar printed circuit board (35)has been attached to the side of the support substrate (21) facing awayfrom the measuring graduation (12) in order to electrically connect thevarious components on the support substrate (21).